The project is a thirty-year follow-up of boys in the Cambridge-Somerville Youth Study. From 1939 to 1945, the homes of 255 boys had been visited approximately twice a month by social workers who recorded their observations. The case records of these observations have been coded by this investigator for physiological, sociological, and psychological variables. The study will trace these individuals from childhood to their mid-forties. Comparisons will be made to ascertain whether children reared in different types of families differ from one another in adult antisocial behavior. Significant antecedents in childhood will be examined in an attempt to distinguish backgrounds among adults manifesting different forms of adult antisocial behavior. The result should be increased understanding of the impact of childhood upon adult criminal behavior.